Sayaka is the lead singer of an incredibly popular idol group. She and Naegi were classmates in middle school. Sayaka once saw Naegi saving a crane stuck in the school pool, and since that has wanted to talk with Naegi.

Seeing as she's an idol, it's expected of Maizono to be a friendly and caring person. Maizono develops a bond with Naegi, whom she considers her friend, assisting him on every occasion. However, she tends to hide her feelings when she is under great pressure by putting on her public persona. She also clings tightly to her band members, and would not hesitate to do something if anything was to happen to one of them, including things that could hurt others.

She is the first one killed in the series, killed by Leon after trying to kill him first with a kitchen knife. She tried to frame Naegi for the murder by switching rooms with him if she had successfully killed Leon. When she did not succeed in murdering Leon, she leaves a dying message by writing "LEON" in her blood. Naegi misreads this as "11037."